Overshoot after current limit!!!

[pswatw]

hi:
I designed a current mode boost converter!
But there is overshoot in vout when current limit release !
It is not easy to slove this problem use traditional soft start!
How to solve this problem!!??
THANKS!!

PSWATW

 

[leo_o2]

A good way for it is to design a soft start circuit for reference voltage. If ref voltage starts up very slowly and smoothly, there is no overshoot on output voltage.

Added after 54 seconds:

Torex (a Japanese IC company) has some ICs to suppress overshoot in this way.

 

[pswatw]

hi: leo_o2

Thanks for your answer!!
But when the current limit occur, the vref is 1.23v!
the vref will not "starts up"

How to solve this problem!!??

 

[pswatw]

HELP!! TELL ME HOW TO SOLVE THIS PROBLEM, PLEASE

 

[leo_o2]

If you make the reference voltage starting up very slowly (>1mS), you don't need to do any change for current limit. You can just design a normal current limit (same current limit level for both before start-up and after start-up). For boost, you need to avoid the fast charging for output cap if you can't turn off the PMOS path (for synchronous boost).